1. Technical Field
The present invention relates to a liquid crystal display device using a lateral electric field drive system and an electronic apparatus including the same.
2. Related Art
In order to realize a wide viewing angle of a liquid crystal display device, a system for generating an electric field in a liquid crystal layer toward a substrate direction and controlling alignment of liquid crystal molecules (hereinafter, referred to as a lateral electric field system) is known. Examples of the lateral electric field system include an in-plane switching (IPS) system and a fringe-field switching (FFS) system.
In general, in a lateral electric field liquid crystal display device, a pair of electrodes for driving a liquid crystal layer is provided on one of a pair of substrates having the liquid crystal layer interposed therebetween. In a FFS liquid crystal display device, one of a pair of electrodes is provided in the vicinity of the surface of a liquid crystal side of a substrate and an alignment film is formed thereon. This alignment film is formed by coating an organic material such as polyimide on one electrode and performing a rubbing process of rubbing the organic material with a rubbing cloth. However, one electrode includes a plurality of band-shaped electrodes with gaps provided therebetween. In addition, since a surface of the substrate on which the alignment film is formed has a fine step difference, a step difference portion is formed in the alignment film due to the step difference. Accordingly, a rubbing process is non-uniformly performed on the step difference portion and the other points and thus light leakage or decrease in alignment regulating force occurs.
Accordingly, a method of forming an alignment film by an optical alignment process using an optical reactive polyimide as an alignment film has been suggested (see, for example, JP-2004-206091). In this alignment process, polarized ultraviolet rays are irradiated onto the surface of the optical reactive polyimide such that an alignment direction according to polarization is formed without being influenced by the fine step difference.
However, even in this alignment process, the following problems occur. That is, in the optical alignment process, the alignment regulating force of liquid crystal molecules due to the alignment film is small and it is difficult to uniformly perform the alignment process. In addition, productivity is low compared with the rubbing process using the rubbing cloth.